The present invention relates to an apparatus for positioning an occupant of a vehicle in an area of a closeable roof hatch.
Vehicles, in particular armored vehicles used by the military or police, normally accommodate several occupants. One occupant, the so-called commander assumes the task to view the situation around the vehicle and to derive conclusions which may possibly be relayed to the other occupants. To enable the commander to reliably survey the surrounding environment, the vehicle involved here has a roof hatch which can normally be closed by a manually operated hatch cover. If the hatch cover is swung open to clear the hatch, the commander is able to stand in the hatch and to monitor the surroundings. For that purpose, the commander oftentimes stands on a seat of a seat formation, occasionally even upon a backrest of such a seat formation.
So long as the vehicle travels on a substantially flat terrain, the commander has no problem to fulfill the job. However, as the vehicle is exposed in addition to natural movements and braking operations to significant spatial vibrations, especially in off-road terrain, the commander has to protect himself or herself from hitting the upper body against the edge of the hatch by moving the upper body as far out as possible from the hatch and using the hands to hold onto external parts of the vehicle for stabilizing the position.
On occasion, occupants are confronted with a situation in which the armored vehicle rolls over. In this case, the commander is exposed and does not have a chance to retract fast enough through the hatch into the interior for safety, when a rollover occurs. Rather, the commander will be hurled out of the vehicle or even crushed by the vehicle. Another dangerous situation for the commander occurs when the vehicle strikes a mine which explodes and then causes the vehicle to tilt. In addition, a strong shock wave is generated which is transmitted through the bottom-mounted seat into the lower leg and thigh as well as spine of the commander, when the vehicle is caused to significantly accelerate in vertical direction as a consequence of the mine explosion.
One approach to address these problems involves to restrain the commander in normal seating position to a mechanically liftable seat by means of a safety belt and to lift the commander with the seat far enough to enable him or her to look out of the hatch for surveying the surroundings. Although this approach secures the commander to the seat assembly, there is still the problem that the seat assembly is coupled to the vehicle bottom. As a result, the commander is forced to follow all motions of the vehicle and thus can be subjected to oftentimes significant accelerating forces. Moreover, such a seat assembly has the drawback that its entire mass including the weight of the commander buckled thereto must be lifted and lowered. Lifting must be implemented by mechanical means because vehicles of this type normally are not equipped with a hydraulic system due to combustibility of hydraulic fluid. When the vehicle rolls over or hits a mine which then explodes, there is not enough time for the mechanic system to respond and move the seat assembly with the commander out of the danger zone in the area of the hatch.
Mechanical lifting of the seat assembly is also disadvantageous because the seat assembly blocks in the upper position the hatch so that the commander, even when unbuckling the safety belt, is unable to stretch in order to leave the vehicle via the hatch with straight legs. Thus, neither the commander nor any of the other occupants has an escape route out of the vehicle, when the seat assembly is secured in the upper position. Finally, there is also a risk that the seat assembly jams in the upper position, as a result of hitting a mine and of the resultant significant high accelerations, and then can no longer be moved downwards. Thus, the hatch is permanently blocked for use as escape route.
It would therefore be desirable and advantageous to provide an improved apparatus for positioning an occupant of a vehicle in an area of a closeable hatch to obviate prior art shortcomings and to enable the occupant to stand in the hatch to reliably assume surveying tasks while still assuring a safe return into the interior of the vehicle, when the vehicle tilts or rolls over or is exposed to a vertical acceleration in the event of an accident of any kind.